Adjustable core turbocharger

ABSTRACT

A turbocharger is provided herein. The turbocharger includes a housing and an adjustable core at least partially circumferentially surrounded by the housing, the adjustable core having a turbine rotor coupled to a compressor rotor via a shaft. The turbocharger further includes an adjustment mechanism coupled to the adjustable core configured to adjust an axial position of the housing relative to the adjustable core in response to adjustment commands.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. patent application Ser.No. 13/333,189, “ADJUSTABLE CORE TURBOCHARGER,” filed on Dec. 21, 2011,the entire contents of which are hereby incorporated by reference forall purposes.

BACKGROUND/SUMMARY

Turbochargers are incorporated into engines to increase the engine'spower to weight ratio. It may be desirable to adjust the flowpath of theexhaust gas into the turbine to facilitate adjustment of the turbine'scharacteristics based on the engine operating conditions. For example,twin scroll turbines have been developed to achieve adjustment of theturbine's characteristics. A twin scroll turbine may include two scrollsfor delivering exhaust gas to the turbine rotor and a valve configuredto adjust the flow-rate of the exhaust gas through the scrolls. Thegeometry of each of the scrolls may be designed to decreases loses overa variety of engine operating conditions. For example, the first scrollmay be sharply angled for a quicker response during lower engine speedsand a second scroll may be less angled to decrease losses during higherengine speeds.

In some twin scroll turbines, an adjustment mechanism may be provided inthe turbine housing which enable adjustment of the exhaust gas flowratethrough each of the scrolls. U.S. Pat. No. 5,855,117 discloses a turbinehousing having two inlet flow passages and an adjustment apparatusintegrated into the housing configured to adjust the flowrate from bothof the inlet flow passages to the turbine rotor. The Inventors haverecognized several drawbacks with this type of design. Variouscomponents in the adjustment mechanism, such as the axial slide member,may be prone to thermal degradation due to the high temperaturesexperienced in the inlets. Moreover, the tolerance required for theaxial slide member may not be achievable within cost targets.Consequently, the losses in the turbine may be increased.

As such in one approach, a turbocharger is provided. The turbochargerincludes a housing and an adjustable core at least partiallycircumferentially surrounded by the housing, the adjustable core havinga turbine rotor coupled to a compressor rotor via a shaft. Theturbocharger further includes an adjustment mechanism coupled to theadjustable core configured to adjust an axial position of the housingrelative to the adjustable core in response to adjustment commands.

When the turbocharger is structured in this way, the adjustmentmechanism may be spaced further away from the high temperature exhaustgas. As a result, the likelihood of thermal degradation of theadjustment mechanism may be reduced, and more reasonable tolerances canbe specified. Therefore, adjustability of the exhaust flow-rate througha turbine scroll is achieved while reducing the likelihood of thermaldegradation of the adjustment mechanism, and meeting cost targets.

The above advantages and other advantages, and features of the presentdescription will be readily apparent from the following DetailedDescription when taken alone or in connection with the accompanyingdrawings. For example, while the examples provided herein show axialdisplacement of the core, rotational displacement (or combinations ofaxial and rotational displacement) may also be used.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic depiction of a turbocharger.

FIG. 2 shows a cross-sectional view of a turbocharger according to anembodiment of the discloser.

FIGS. 3-4 show the adjustable core in the turbocharger illustrated inFIG. 2 in different axial positions.

FIGS. 5-8 show several embodiments of the adjustment mechanism includedin the turbocharger shown in FIG. 1.

FIGS. 9-12 show various embodiments of the housing of the turbochargershown in FIG. 1.

FIG. 13 shows a method for controlling a turbocharger.

FIGS. 2-12 are drawn approximately to scale.

DETAILED DESCRIPTION

Embodiments of a turbocharger having an adjustable core are describedherein. The adjustable core of the turbocharger is configured to axiallyadjust with respect to the turbocharger housing, the housing including acompressor volute and a turbine scroll. The adjustable core includes theturbine and compressor rotors, the shaft coupling the turbine andcompressor rotors, and other components that are explained in greaterdetail herein. In one example, movement of the core thus includesmovement of the turbine and compressor rotors, the shaft, etc. In thisway, the flowrate of fresh air into/out of the compressor and/or exhaustgas into/out of the turbine can be adjusted since the compressor and/orthe turbine can communicate to a greater or lesser degree with flowopenings in the housing of the compressor volute/turbine scrolls, forexample. When the entire adjustable core is adjusted, it will beappreciated that the longevity and robustness of the turbocharger may beincreased when compared to other turbochargers using an adjustmentmechanism integrated into the housing of the turbine, to adjust theexhaust gas flowrate into the turbine.

FIG. 1 shows a schematic depiction of an engine 100 having aturbocharger 150. The engine includes an intake system 104 and anexhaust system 106. The intake system 104 is configured to provide acombustion chamber 108 with intake air and may include components suchas a throttle, an intake manifold, etc., to accomplish thisfunctionality. On the other hand the exhaust system 106 is configured toreceive exhaust gas from the combustion chamber 108 and may includecomponents such as an exhaust manifold, an emission control device(e.g., catalyst, particulate filter), etc. Arrow 105 represents the flowof intake air into the intake system 104. Likewise, arrow 107 representsthe flow of exhaust gas to the surrounding environment from the exhaustsystem 106.

The combustion chamber 108 may include an intake valve 110 and anexhaust valve 112 coupled thereto. The intake and exhaust valves (110and 112) may be operated to perform a combustion cycle such as a fourstroke combustion cycle (e.g., intake, compression, power, exhaust).Arrow 114 represents the flow of intake air into the combustion chamber108 from the intake system 104 and arrow 116 represents the flow ofexhaust gas from the combustion chamber 108 to the exhaust system 106.Additionally, the engine 100 may further include a fuel delivery system(not shown) configured to supply fuel to the combustion chamber 108and/or a spark plug configured to initiate combustion in the combustionchamber.

The engine 100 further includes a turbocharger 150 having a compressor152 and a turbine 154, the compressor having a compressor rotor 156 andthe turbine including a turbine rotor 158. The turbine 154 may be drivenvia exhaust gas flow. Likewise, the compressor 152 may be configured toincrease the pressure of the intake air. In this way, the power outputand/or the efficiency of the engine 100 is increased.

The turbocharger 150 may further include a shaft 160 rotatably couplingthe compressor rotor 156 to the turbine rotor 158. The turbine rotor158, compressor rotor 156, and the shaft 160 are included in anadjustable core 161. As discussed in greater detail herein, theadjustable core 161 may be an axially adjustable core. A housing 162circumferentially surrounds at least a portion of the adjustable core161. In one example, the housing 162 circumferentially encloses thecompressor rotor 156, the turbine rotor 158, and the shaft 160.

The turbocharger 150 further includes an adjustment mechanism 164configured to adjust the axial position of an adjustable core 161relative to the housing 162. The turbocharger 150 enables the flowrateinto the turbine and outflow of the compressor to be controlled based onthe operating conditions within the engine. As a result, combustionefficiency and/or power output of the engine is increased.

The engine 100 may further include a controller 130 configured to adjustvarious components in the engine 100. Specifically, the controller 130is configured to send adjustment commands to the adjustment mechanism164 to initiate axial adjustment of the adjustable core 161 relative tothe housing 162. Thus the adjustable core 161 may be moved in eitheraxial direction to alter the flowrate of exhaust gas into the turbine154, discussed in greater detail herein with regard to FIGS. 2-4. Thecontroller 130 may be a conventional microcomputer including:microprocessor unit 132, input/output ports 134, read-only memory 136,random access memory 138, keep alive memory 140, and a conventional databus.

FIG. 2 shows an illustration of a cross-section of a first embodiment ofthe turbocharger 150. As shown, the turbocharger 150 includes thehousing 162. The housing 162 includes a compressor volute 200 configuredto receive the outflow of the compressor 152. Wall 203 defines theboundary of the compressor volute passage 201.

It will be appreciated that the compressor volute 200 maycircumferentially extend around the compressor rotor 156 in a spiralmanner.

The housing 162 includes a first turbine scroll 202 and a second turbinescroll 204. The first turbine scroll includes wall 206 defining theboundary of a first turbine scroll passage 208. Likewise, the secondturbine scroll includes wall 210 defining a boundary of a second turbinescroll passage 212. It will be appreciated that both of the turbinescroll passage are configured to direct exhaust gas to the turbine rotor158. Furthermore, the adjustment mechanism 164 may adjust the adjustablecore 161 to alter the exhaust gas flow through the first and/or secondturbine scroll passages (208 and 212). The first turbine scroll 202 mayhave different geometric characteristics than the second turbine scroll204. Specifically, the first turbine scroll 202 may have a geometryconfigured to increase turbine efficiency at lower engine speeds and thesecond turbine scroll 204 may have a geometry configured to increaseturbine efficiency at higher engine speeds. For example, the firstturbine scroll 202 may have a steeper entry angle than the secondturbine scroll 204 or visa-versa. The entry angle of the scroll may bedefined as the angle between the line of mean flow momentum intersectingthe turbine wheel and a line extended from this intersection pointtangent to the perimeter of the scroll in a plane perpendicular to therotational axis of the scroll. However, in other embodiments the housing162 may include only a single turbine scroll.

During operation of the turbocharger 150, air may flow into thecompressor 152 via the compressor inlet passage 214 and flow out to thecombustion chamber 108 via the compressor volute 200. Additionally,exhaust from the combustion chamber 108 may enter the turbine 154 viathe first and second turbine scrolls (202 and 204) and flow out of theturbine 154 via the turbine outlet passage 216. The outflow of theturbine 154 may be directed to an emission control device and then thesurrounding atmosphere in some embodiments.

The turbocharger 150 further includes the adjustable core 161 at leastpartially enclosed via housing 162. The adjustable core 161 may bedivided into several sections including a central core section 218interposed between a first peripheral core section 220 and a secondperipheral core section 222.

The central core section 218 includes the shaft 160, one or morebearings 224 configured to facilitate rotation of the shaft 160, and ashaft housing 226 at least partially enclosing the shaft 160. Thecentral core section 218 axially extends from the turbine rotor 158 tothe compressor rotor 156.

The first peripheral core section 220 includes a compressor flow guide228. The compressor flow guide 228 is configured to direct intake airinto the compressor rotor 156 and direct intake air from the compressorrotor 156 to the compressor volute 200. Thus, the compressor flow guide228 may be fluidically coupled between the compressor rotor 156 and thecompressor volute 200. Likewise, the turbine flow guide 230 isconfigured to direct exhaust gas from the first and second scrollpassages (208 and 212) to the turbine rotor 158 and direct exhaust gasfrom the turbine rotor 158 to the exhaust system 106, shown in FIG. 1.Thus, the turbine flow guide 230 may be fluidically coupled between theturbine rotor 158 and the first and second scroll passages (208 and212). The turbine flow guide 230 can be axially adjusted to alter theflowrate of exhaust gas into the turbine rotor 158. Likewise, thecompressor flow guide 228 can be axially adjusted to alter the flowrateof intake air into the volute passage 201. As discussed in greaterdetail herein, the first peripheral core section 220 may be coupled tothe central core section 218 via a plurality of slotted extension 500,shown in FIG. 5, discussed in greater detail herein. In this way, therelative position of the central core section and the first peripheralcore section 220 is substantially fixed. Thus, the axial position of thecentral core section 218 and the first peripheral core section 220 maybe correspondingly adjusted. Likewise, the second peripheral coresection 222 may be coupled to the central core section via a pluralityof slotted extensions 502, shown in FIG. 5. In this way, the relativeposition of the central core section 218 and the second peripheral coresection 222 is substantially fixed. Therefore, the axial position of thecentral core section 218, the first peripheral core section 220, and thesecond peripheral core section 222 may be correspondingly adjusted. Inthis way, both the geometry (e.g., area) of the flow opening intocompressor 152 and the flow openings into turbine 154 may be adjustedbased on engine operating conditions to increase the efficiency of theturbocharger 150 through axial movement of the core 161 and specificallythe compressor flow guide 228 and the turbine flow guide 230, therebyenabling increased the engine power output and/or efficiency.

The turbocharger 150 also includes a lubrication system 232 including alubrication passage 234 traversing the central core section 218. Branchpassages 236 may be fluidly coupled to the lubrication passage 234 andconfigured to supply oil or other suitable lubricant to the bearings224. In this way, wear on the bearings 224 is reduced. The lubricationsystem 232 further includes a feed passage 238 integrated into thehousing 162. It will be appreciated that the feed passage 238 may becoupled to a lubrication circuit including a pump in the engine 100,shown in FIG. 1. In this way, lubricant can be delivered to the feedpassage 238.

A first embodiment of the adjustment mechanism 164 is shown in FIG. 2.As shown the turbine flow guide 230 is substantially obstructing flowfrom the second scroll passage 212 to the turbine rotor 158. In thisway, exhaust gas flow may be substantially inhibiting from the secondscroll passage 212 to the turbine rotor 158. The turbine flow guide 230may be positioned in this manner when a pressure ratio >1.0 (i.e. boost)is desired but absolute mass air flow is limited, such as for a lowspeed tip-in. In this way, the effective volume of the turbine isreduced to achieve faster transient response. On the other hand, thecompressor flow guide 228 is directing intake air from the compressorrotor 156 to the leading axial edge of the volute passage 201. Theadjustment mechanism includes an adjustment post 240 directly coupled tothe adjustable core 161 and a track 242 integrated into the housing 162.Specifically, the adjustment post 240 is moveably positioned in thetrack 242. The track 242 may extend in an axial direct and may beparallel to the axis 244 of rotation of the turbocharger 150. However,the position of the track 242 may be altered in other embodiments. Anaxial force 300 may be applied to the adjustment post 240 to alter theadjustable core's 161 axial position, as shown in FIGS. 3 and 4.Therefore, FIGS. 3-4 show various axial positions of the turbocharger150. In this way, the adjustable core 161 is an axially adjustable core.It will be appreciated that the adjustment mechanism 164 may slide thecompressor rotor 156 relative to the volute and the turbine rotor 158relative to the first and second scrolls (202 and 204) concurrently. Itwill be appreciated that although 3 axial positions are shown in FIGS.2-4, the turbocharger 150 may be arranged in a large number of positionsand specifically in some embodiments the adjustable core may becontinuously adjustable. However, in other embodiments the adjustablecore may be adjustable in a plurality of discrete positions.

Specifically, FIG. 3 shows a configuration of the turbocharger 150 wherethe turbine flow guide 230 is partially obstructing flow from the secondscroll passage 212 to the turbine rotor 158. Furthermore, the compressorflow guide 228 is positioned in the middle of the outlet 302 of thecompressor volute passage 201. It will be appreciated that when thecompressor 152 is configured in this way the restriction of the airflowthrough the compressor is similar for settings as shown in FIG. 3 andFIG. 2. Therefore the boost provided by the turbocharger 150 may beincreased when compared to the configuration shown in FIG. 2 because thefirst scroll passage 208 and a portion of the second scroll passage 212are capturing the exhaust flow, thereby increasing the speed turbinerotor 158 and therefore the compressor rotor 156. However, it will beappreciated that the configuration shown in FIG. 3 may have a slowertransient response than the configuration shown in FIG. 2, due to theincrease scroll passage volume through which exhaust gas is traveling inFIG. 3. In this way, the compressor outlet flow and therefore the boostprovided by the turbocharger 150 may be adjusted via an adjustable core161. Likewise, the compressor flow guide 228 directs air flow from thecompressor rotor 156 to an outer axial edge of the volute passage 201.In this way, the flow rate and mass flow of the intake air into thecompressor rotor 156 is increased, thereby increasing boost provided bythe turbocharger 150. It will be appreciated that the turbocharger 150may be configured in this position when matching the desired boost tothe mass flow requirement without venting exhaust energy through thewastegate. For instance, this could be desired when transitioning fromlight load to mid throttle operation or when transitioning from moderateboost levels to mid boost levels.

FIG. 4 shows a configuration of the turbocharger 150 where the turbineflow guide 230 is not obstructing flow from the first or second scroll(202 and 204) to the turbine rotor 158. In this way, exhaust may beflowed through both scrolls (202 and 204) during turbocharger operation.Therefore, the flowrate of exhaust gas from the scrolls into the turbinerotor 158 is increased, thereby increasing the velocity of the turbinerotor 158 and therefore the compressor rotor 156, when compared to theturbocharger configuration shown in FIGS. 2 and 3. As a result, theboost provided by the turbocharger 150 is increased. Additionally, thecompressor flow guide 228 is positioned near the right axial peripheryof the outlet 302 of the compressor volute passage 201. When thecompressor flow guide 228 is positioned in this way the restriction ofthe intake air flow through the outlet of the compressor 152 is notsubstantially different when compared to the configuration shown inFIGS. 2 and 3. However, the increase in exhaust energy capture due tofull utilization of both scrolls increases compressor speed, therebyincreasing boost provided by turbocharger 150 {. It will be appreciatedthat the turbocharger 150 may be configured in this position when fullflow potential is desired such as at medium load high speed, and high orfull load conditions.

FIG. 5 shows an illustration of the adjustable core 161 and theadjustment mechanism 164 shown in FIGS. 2-4. Furthermore, FIGS. 6-8 showdifferent embodiments of the adjustment mechanism 164 and the adjustablecore 161 shown in FIG. 1. It will be appreciated that the controller 130shown in FIG. 1 may be used to control the various embodiments of theadjustment mechanism shown in FIGS. 5-7.

Specifically, FIG. 5 shows the first embodiment of the adjustmentmechanism 164 using axial input to adjust the relative position of theadjustable core 161 and the housing 162. As shown the adjustment post240 is coupled to the adjustable core 161. Specifically, the adjustmentpost 240 is coupled to the central core section 218. However, in otherembodiments the adjustment post 240 may be coupled to the first orsecond peripheral core sections (220 and 222). An axial force may beapplied to the adjustment post 240 to more the adjustable core 161 in anaxial direction. It will be appreciated that the housing 162 may includetrack 242, shown in FIG. 2, extending in the axial direction to guidethe adjustment post 240 in a desired direction. A suitable component,such as a solenoid valve may be used to apply the axial force to theadjustment post 240. In this way, the axial position of the adjustablecore 161 may be adjusted based on the operating conditions of theengine. Specifically, the compressor flow guide 228 and the turbine flowguide 230 are axially adjusted responsive to the force applied to theadjustment post 240 and therefore alter the flowrate of the intake airentering the compressor volute 200 from the compressor rotor 156, shownin FIG. 2, and the exhaust gas flowrate from the second turbine scroll204, shown in FIG. 2, to the turbine rotor 158.

FIG. 5 further illustrates the first peripheral core section 220, thecentral core section 218, and the second peripheral core section 222 aredepicted. The first peripheral core section 220 is fixedly coupled tothe central core section 218 via slotted extensions 500. The slottedextensions 500 may extend across a portion of an inlet of the compressorvolute 200 shown in FIG. 2. Likewise, the second peripheral core section222 is fixedly coupled to the central core section 218 via slottedextensions 502. The slotted extensions 502 may extend across a portionof the outlets of the first and second scrolls 202 and 204, shown inFIG. 2. The slotted extensions 500 and 502 are axially aligned with therotational axis 244 of the turbocharger 150, in the embodiment depictedin FIG. 5. However, in other embodiments the slotted extensions 500 and502 may be alternately positioned. In this way, the relative positionsof the first peripheral core section 220, the central core section, andthe second peripheral core section 222 are fixed relative to one anotherand therefore may simultaneously move in response to an axial forceapplied thereto. The compressor rotor 156 and the turbine rotor 158 arealso shown in FIG. 5. A component schematically depicted at 504 may beconfigured to apply an axial force to the adjustment post 240 inresponse to adjustment commands sent from the controller 130 shown inFIG. 1. The component depicted at 504 may be in wired/wirelesscommunication with the controller 130, shown in FIG. 1. In this way, thecontroller 130 can be used to adjust the axial position of theadjustable core 161 relative to the housing 162.

FIG. 6 shows a second embodiment of the adjustment mechanism 164 shownin FIG. 1. The adjustment mechanism includes the adjustment post 240 andthe track 242. However, the track 242 extends in an axial as well as aradial direction in the embodiment depicted in FIG. 6. Therefore, thetrack 242 includes a first end 610 axially offset from a second end 612.The adjustment post 240 is shown fixedly coupled to the central coresection 218 in the depicted embodiment. However, in other embodimentsthe adjustment post 240 may be coupled to the first or second peripheralcore sections (220 and 222). The adjustment mechanism 164 furtherincludes a rotational component 600 including a first gear wheel 602configured to mesh with a second gear wheel 604 integrated into theadjustable core 161. As shown each of the gear wheels (602 and 604)include gear teeth 606. The second gear wheel 604 is integrated into thefirst peripheral core section 220. However, in other embodiments thesecond gear wheel 604 may be integrated into the central core section218 or the second peripheral core section 222. A component depicted at608 may be configured to rotate gear wheel 602 in response to adjustmentcommands sent from the controller 130 shown in FIG. 1. In turn, thesecond gear wheel 604 rotates and the adjustment post 240 travelsaxially through track 242. In this way, the controller 130 can be usedto adjust the axial position of the adjustable core 161. Specifically,the compressor flow guide 228 and the turbine flow guide 230 are axiallyadjusted responsive to the rotation of gear wheel 602 via component 608and therefore alter the flowrate of the intake air entering thecompressor volute 200 from the compressor rotor 156, shown in FIG. 2,and the exhaust gas flowrate from the second turbine scroll 204, shownin FIG. 2, to the turbine rotor 158. Furthermore, the component depictedat 608 may be in wired/wireless communication with the controller 130,shown in FIG. 1.

FIG. 7 shows a third embodiment of adjustment mechanism 164, shown inFIG. 1. As shown the adjustment mechanism 164 includes the adjustmentpost 240 and the track 242, shown in FIG. 6. The track 242 extends in anaxial as well as a radial direction. However, in the embodiment depictedin FIG. 7, a component, schematically depicted at 700, is configured toapply a vertical force 702 to the adjustment post 240. When the verticalforce is applied to the adjustment post 240, the adjustable core 261moves in an axial direction. The adjustment mechanism further includesan extension 700 fixedly coupled to the central core section 218. Thecore guide 704 is configured to guide the movement of the adjustablecore 161 during adjustment. The component 700 is may be configured toapply the vertical force 702 in response to adjustment commands from thecontroller 130 shown in FIG. 1. In response to the vertical force 702the adjustment post 240 moves vertically as well as axially in the track242. In this way, the controller 130 can be used to adjust the axialposition of the adjustable core 161. Specifically, the compressor flowguide 228 and the turbine flow guide 230 are axially adjusted responsiveto the vertical force 702 generated via component 700 and thereforealter the flowrate of the intake air entering the compressor volute 200from the compressor rotor 156, shown in FIG. 2, and the exhaust gasflowrate from the second turbine scroll 204, shown in FIG. 2, to theturbine rotor 158.

FIG. 8 shows a fourth embodiment of the adjustment mechanism 164 shownin FIG. 1. As show the adjustment mechanism 164 is hydraulic. Theadjustment mechanism 164 includes a supply line 800, a return line 802,a chamber 804 partially enclosing a hydraulic piston 806, and a spring808. The supply line 800 may be configured to increase the oil pressurein chamber 804 to move hydraulic piston 806 in an axial direction. Inthis way, hydraulic inputs may be used to move the adjustable core 161.The hydraulic piston 806 may be fixedly coupled to the central coresection 218. In this way, the central core section 218 can be moved inan axial direction hydraulically. It will be appreciated that the spring808 provides a return force to the hydraulic piston 806. In this way,the hydraulic piston 806 and the central core section 218 can bereturned to its original positioned when the oil pressure in the chamber804 is decreased. The chamber 804 and/or hydraulic piston 806 maycircumferentially extend around the central core section 218. Inresponse to movement of the hydraulic piston 806 generated through apressure adjustment in the supply line 800 the axial position of theadjustable core 161 is altered. Specifically, the compressor flow guide228 and the turbine flow guide 230 are axially adjusted responsive tomovement of the hydraulic piston 806 and therefore alter the flowrate ofthe intake air entering the compressor volute 200 from the compressorrotor 156, shown in FIG. 2, and the exhaust gas flowrate from the secondturbine scroll 204, shown in FIG. 2, to the turbine rotor 158.

The chamber 804 is fluidly coupled to the lubrication passage 234, inthe depicted embodiment. A check valve 810 may be coupled to thelubrication passage 234. The check valve 810 may be configured to openand decrease the pressure in the lubrication passage 234 when thepressure exceeds a predetermined threshold value. However, in otherembodiments a separately feed passage may supply oil to the lubricationpassage 234.

FIGS. 9-12 show various embodiments of the housing 162 of theturbocharger 150. In the embodiment shown in FIG. 2 the housing forms acontinuous surface and is cast via a single casting. However, in theembodiments shown in FIGS. 9-12 a portion of the housing may beseparately constructed (e.g., cast, machined, etc.). Specifically, FIG.9 shows a divider 900 defining the boundary between the first and secondscroll passages (208 and 212) separately manufactured and then coupledto remainder of the housing 162. Thus, the divider 900 may separate thefirst scroll passage 208 from the second scroll passage 212. It will beappreciated that the housing 162 and the first and the divider 900 maybe constructed out of separate materials. For example, the material usedto construct the housing 162 may include a high series stainless steel,such as a D5S material. On the other hand, the materials that may beused to construct the divider 900 may include high nickel contentstainless alloy such as inconel or an A5N material or Din1.4848material. It will be appreciated that the material used toconstruct the divider 900 may be less prone to thermal degradation thanthe material used to construct the remainder of the housing 162. In thisway, the longevity of the turbocharger 150 may be increased whencompared to turbochargers using a single material to construct thehousing.

FIG. 10 shows an expanded view of the divider 900 shown in FIG. 9. Asshown the section of housing including the first and second scrolls maybe welded to the housing 162 via welds such as spot welds 1000. Thedivider 900 may also include a heat resistant coating 1002.Additionally, FIG. 11 shows the divider 900 coupled to the housing 162via a bolt 1100. However, in other embodiments it will be appreciatedthat other suitable coupling techniques may be utilized.

In the embodiment shown in FIG. 12, the divider 900 is shown coupled tothe housing 162. A coolant passage 1200 extends through the divider 900.The coolant passage 1200 is configured to circulate coolant through thedivider 900 to remove heat from the turbine 154. The coolant passage1200 may circumferentially extend 360 degrees around the adjustable core161. The coolant passage 1200 may be coupled to a heat exchangerconfigured to remove heat from the coolant circulated through thecoolant passage.

FIG. 13 shows a method 1300 for controlling a turbocharger. The method1300 may be implemented via the turbocharger, controller, components,etc., described above with regard to FIGS. 1-12 or may be implementedvia another suitable turbocharger, controller, components, etc.

At 1302 the method includes determining if turbocharger adjustment hasbeen requested. If turbocharger adjustment is not requested (NO at 1302)the method ends. However, if turbocharger adjustment is requested (YESat 1302) the method proceeds to 1304. At 1304 the method includesadjusting one or more of compressor outlet flow and turbine inlet flowof the turbocharger via axially sliding a shaft coupling a compressorrotor and a turbine rotor within a fixed housing. The adjusting at 1304may include at 1306 decreasing or increasing the flowrate of exhaust gasfrom a turbine scroll to the turbine rotor and at 1308 decreasing orincreasing the flowrate of exhaust gas the compressor rotor to thecompressor volute.

This concludes the description. The reading of it by those skilled inthe art would bring to mind many alterations and modifications withoutdeparting from the spirit and the scope of the description. For example,single cylinder, I2, I3, I4, I5, V6, V8, V10, V12 and V16 enginesoperating in natural gas, gasoline, diesel, or alternative fuelconfigurations could use the present description to advantage.

The invention claimed is:
 1. A method for a turbocharger comprising:adjusting an adjustment mechanism of the turbocharger in response tooperating conditions of an engine, the turbocharger including a housingand an adjustable core circumferentially surrounded by the housing, theadjustable core axially slideable relative to the housing and includinga turbine rotor coupled to a compressor rotor via a shaft, theadjustment mechanism coupled to the adjustable core, the adjustable coresliding the compressor rotor and the turbine rotor concurrently.
 2. Themethod of claim 1, wherein the housing includes a compressor volute anda turbine scroll, the compressor volute configured to receive air fromthe compressor rotor and the turbine scroll configured to direct exhaustgas into the turbine rotor, wherein the adjustable core slides thecompressor rotor relative to the compressor volute and the turbine rotorrelative to the turbine scroll concurrently.
 3. The method of claim 2,further comprising a second turbine scroll configured to direct exhaustgas to the turbine rotor.
 4. The method of claim 3, wherein the firstand second turbine scrolls are separated via a divider.
 5. The method ofclaim 4, wherein the divider includes a coolant passage configured toflow coolant therethrough.
 6. The method of claim 1, wherein theadjustable core includes an adjustment post extending therefrom.
 7. Themethod of claim 6, wherein the adjustment post is moveably positioned ina track.
 8. The method of claim 7, wherein the track circumferentiallyextends around the adjustable core and includes a first end axiallyoffset from a second end.
 9. The method of claim 1, wherein the shaftcoupling the turbine rotor and the compressor rotor is axiallyadjustable.
 10. A turbocharger comprising: a housing; an axiallyadjustable core circumferentially surrounded by the housing, the coreincluding a turbine rotor coupled to a compressor rotor via a shaft, acompressor flow guide fluidically coupled between a volute and thecompressor rotor, and a turbine flow guide fluidically coupled between afirst and a second turbine scroll and the turbine rotor; and a dividerseparating the first and second turbine scrolls.
 11. The turbocharger ofclaim 10, wherein the divider includes a coolant passage configured toflow coolant therethrough.
 12. The turbocharger of claim 10, furthercomprising an adjustment mechanism coupled to the axially adjustablecore configured to adjust an axial position of the housing relative tothe axially adjustable core in response to adjustment commands.
 13. Theturbocharger of claim 10, wherein the first turbine scroll has adifferent geometry than the second turbine scroll.
 14. The turbochargerof claim 10, wherein the axially adjustable core slides the compressorrotor relative to the volute and the turbine rotor relative to the firstand second turbine scrolls concurrently.
 15. A turbocharger controlmethod, comprising: adjusting one or more of compressor outlet flow andturbine inlet flow of a turbocharger via axially sliding a shaftcoupling a compressor rotor and a turbine rotor within a fixed housingduring turbocharger operation, the turbocharger coupled to an internalcombustion engine.
 16. The turbocharger control method of claim 15,wherein adjusting one or more of compressor outlet flow and turbineinlet flow includes decreasing or increasing a flowrate of exhaust gasfrom a turbine scroll to the turbine rotor.
 17. The turbocharger controlmethod of claim 15, wherein adjusting one or more of compressor outletflow and turbine inlet flow includes substantially inhibiting flow ofexhaust gas from a turbine scroll to the turbine rotor.
 18. Theturbocharger control method of claim 15, wherein adjusting one or moreof compressor outlet flow and turbine inlet flow is responsive to engineload.